Relay apparatus



July 16, 1935. R. J. WENSLEY RELAY APPARATUS Filed Feb. 21, 1954 INVENTOR 1909f Nana/e} I WITNESSES: 5d 4%? Patented July 16, 1935 RELAY APPARATUS Roy J. Wensley, Bloomfield, N. 1., assignor to Westinghouse Electric & Manufacturing Company, East Pittsburgh, Pa., a corporation of Pennsylvania Application February 21,1934, Serial No. 712,337 11 Claims. (01.- 175 294) My invention relates to relay apparatus and particularly to a novel means for reducing the destructive action of electric currents upon relay contacts. Although of general utility in connection with relays, my invention is particularly applicable to high-speed relays as used in connection with high-speed circuit, breaker apparatus. It is the present practice in connection with alternating-current transmission to provide protective apparatus in which the overall clearing time of the circuit breakers may be as low as a few cycles of a 60 cycle supply. I

In such apparatus the time permitted for operation of a protective relay may be of the order of one cycle, and, in general, special designs of both the relay and circuit breaker are necessary to obtain the high-speed action. The moving However, as the magnetic energy which can be,

stored by the trip coil is proportional to the product of the inductance of the trip coil and "the square of the tripping current, it is necessary that the tripping current be large in order to secure adequate mechanical force to release the circuit breaker latch, with the small value of inductance present. As the tripping current is necessarily large, a problem arises in providing relay contacts which are sufficiently light for high speed action and yet have suflicient current carrying capacity to insure reliability and reasonable life.

It is an object of my invention to provide a novel high-speed relay arrangement in which large tripping currents shall be used, but in which the duty of the relay contacts shall be greatly reduced.

Another object of my invention is to provide a novel high speed relay arrangement in which a make-alive electric discharge device shall be used to relieve the duty of the relay contacts.

Other objects of my invention will become evident from the following detailed description taken in conjunction with the accompanying drawing in which the single figure is a diagrammatic view of a high-speed relay arrangement embodying my invention.

Referring to the drawing in detail, an electric circuit I, which may be a transmission conductor or feeder, is controlled by means of a high-speed circuit breaker shown diagrammatically at 2.

The circuit breaker 2 is biased to open position and is held closed by means, of suitable latching mechanism 3, arranged to be released in response to energization of a trip coil 4 in a manner well understood in the art. The trip coil 4 is designed so that its ratio of inductance to resistance is small.

The trip coil 4 is connected in series with a set of auxiliary contacts 5 of the circuit breaker 2, a storage battery 6 and a makealive electric discharge device 1, preferably of the type disclosed in the copending application of D. D. Knowles, Serial No. 690,701, filed Sept. 23, 1933, and assigned to the Westinghouse Electric and Manufacturing Company.

The electric discharge device I comprises a sealed envelope 1a in which are mounted an anode 8, suitably spaced from a cathode pool 8,

of mercury or other suitable vaporizable are medium, and a, control or starting electrode I 0. The control electrode' H1 is preferably of a suitable crystalline material such as carborundum and is in contact with the cathode pool 9. An electricdischarge device of the type described has the characteristic that if a current of the order of 3 to. 15 amperes is circulated through the control electrode lo, a cathode spot forms upon the mercury pool 9, and if the anode 8 is maintained at a positive potential with reference to the cathode pool 9, an arc discharge starts between the latter two electrodes. As the are impedance is negligible compared to the impedance of the carborundum control electrode Hi, the current through the control electrode I0 falls to substantially zero when the arc starts, if the control electrode Ill and anode 8 are connected to the-same voltage source. The action described takes place very rapidly, the current flow in the control electrode l0 lasting for only a few microseconds.

The relay whose contacts are to be protected is shown as an instantaneous type overcurrent element ll, arranged to connect the control electrode ID to the anode 8. It will be understood that in a practical embodiment of my invention as applied to high-speed protective apparatus, the relay ll would assume the form of one of the more eleaborate high-speed relay arrangements familiar to those skilled in the art.

The operation of the above described apparatus may be set forth as follows: Upon the occurrence of an abnormal condition, such as a fault, to which the relay H responds, the latter clos'es its contacts and connects the control electrode 10' to the positive pole of the battery 8. It frequently happens in an actual protective system, that the relay contacts chatter orbounce upon operation of the relay as the relay closing force may barely exceed the bias at times of accurate discriminatory operation. However, in accordance with my invention, upon the first engagement of the relay contacts, current flows through the control electrode l and within a few micro-seconds an are starts between the anode 8 and cathode pool 9. If the relay contacts bounce, no arcing occurs at the contacts as the latter are efiectively short circuited by the arc in the device 7, before the contacts separate after the first engagement.

' As the inductance of the trip circuit is low compared to its resistance, the inductive time lag of the trip circuit is negligible, and the circuit breaker 2 is opened within a few cycles. Upon the opening of the circuit breaker 2, the arc circuit is interrupted at the contact 5, and the relay l I drops out. The circuit breaker 2 may be reclosed manually or automatically by means familiar to those skilled in the art.

As the tripping current fiows'through the contacts of the relay ll for only a few micro-seconds, the heat generated at the contacts is negligible even though the tripping current is comparatively large, and the usual destructive action of the tripping current is avoided. Because of the almost instantaneous short-circuiting .action of the discharge device 7, the relay contacts are never called upon to interrupt a current of appreciable magnitude, even though chattering and bouncing occur.

I do not intend that the present invention shall be restricted to the specific structural details, arrangement of parts or circuit connections herein set forth as various modifications thereof may be efiected without departing from the spirit and scope of my invention. I desire therefore that only such limitations shall be imposed as are indicated in the appended claims.

I claim as my invention 1. In combination -with a relay having contacts, an electric discharge device having principal electrodes effective to complete a normally high impedance shunt path in paralled to said contacts and having a control electrode effective upon engagement of said contacts to reduce the impedance of said shunt path.

2. In combination with a relay having contacts, an electro-ionic device having principal electrodes effective to complete a normally nonconducting shunt path in parallel to said contacts and having a control electrode efi'ective upon engagement of said contacts to render said shunt path conducting.

3. In combination with a relay having contacts, a make-alive electro-ionic device having principal electrodes effective to complete a normally non-conducting shunt path in parallel to said contacts and having a starting electrode efiective upon engagement of said contacts to initiate an arc discharge between said principal electrodes.

4. In combination with a translating device having an output circuit of limited current carrying capacity, a make-alive electro-ionic device having principal electrodes effective to complete a normally non-conducting shunt path in parallel to said output circuit, and having a starting electrode effective upon energization of said output circuit to initiate an arc discharge between said principal electrodes, to thereby reduce the impedance of said shunt path as compared with that of-said output circuit.

5. In combination with a relay having contacts,

electro-responsive means controlled by said relay, an electric discharge device having principal electrodes arranged to provide a normallyhigh impedance discharge path and having a control electrode effective when energized electrically to a predetermined degree to reduce the impedance of said discharge path, a source, conductors completing a circuit including said electro-responsive means, said source and said principal electrodes in series and including said contacts in a path in parallel to said principal electrodes, said control electrode being connected with said circuit at a point such that said control electrode becomes energized to said predetermined degree in response to engagement of said contacts.

6. In combination with arelay having contacts, electro-responsive means controlled by said relay, an electro-ionic device having principal electrodes arranged to provide a normally non-conducting discharge path and having a control electrode efiective when energized electrically to a predetermined degree to render said discharge path conducting, a source, conductors completing a circuit including said electro-responsive means, said source and said principal electrodes in series and including said contacts in a path in parallel to said principal electrodes, said control electrode being connected with said circuit at a point such that said control electrode becomes energized to said predetermined degree in response to engagement of said contacts.

7 In combination with a relay having contacts, electro-responsive means controlled by said relay, an electro-ionic device having a cathode and anode arranged to provide a normally non-conducting discharge path and having a starting electrode in conductive relationship to said cathod'e, said starting electrode being effective in response to a current of predetermined value therethrough to render said discharge path conducting, a source, conductors completing a circuit including said electro-responsive means, said source, said cathode and said anode in series and including said contacts in a path in parallel to said cathode and anode, said starting electrode being connected with said circuit at a point such that a currentof at least said predetermined value-is circulated through said starting electrode in response to engagement of said contacts.

8. In protective apparatus for an electric circuit, a circuit breaker having a trip coil, protective relay means having contacts, a trip circuit including said coil and said contacts, and an electric discharge device having electrodes connected with said trip circuit to form a shunt discharge path around said contacts, said device having characteristics such that said shunt discharge path becomes conducting upon operation of said relay means.

9. In protective apparatus for an electric circuit, a circuit breaker having a tripcoil, protective relay means having contacts, a trip circuit including said coil and said contacts, and an electric, discharge device having principal electrodes connected with said trip circuit to form a shunt discharge path around said contacts and having a control electrode efiective to render said discharge path conducting upon engagement of said contacts.

10. In high-speed protective apparatus, a highspeed circuit breaker having a trip coil of comparatively low inductance, high-speed relay means having contacts, a trip circuit including said coil and said contacts, said trip circuit having a comparatively low ratio of inductance to resistance, and an electric discharge device having principal electrodes connected with said trip circuit to form a shunt discharge path around said contacts and having a control electrode effective to render said discharge path conducting upon engagement 01' said contacts.

11. In high-speed protective apparatus, a highspeed circuit breaker having a trip coil of comparatively low inductance, high-speed relay means having contacts, an electro-ionic device having a cathode and anode arranged to provide a normally non-conducting discharge path and having a starting electrode in conductive relationship to said cathode,'said starting electrode being eitective in response to a current of predetermined value therethrough to render said discharge path conducting, a source, conductors completing a trip circuit including said trip coil, said source. said cathode and said anode in series and including said contacts in a path in parallel to said cathode and anode, said trip circuit having a comparatively low ratio of inductance to resistance, said starting electrode being connected with said trip circuit at a point such that a current of at least said predetermined value is circulated through said starting electrode in response to engagement of said contacts.

ROY J. WENBLEY. 

